In an information recording medium, such as a DVD-ROM (DVD-Read Only Memory), a DVD-R (DVD-Recordable), and a BD-ROM, there is also developed a multilayer type or dual-layer type optical disc or the like on which a plurality of recording layers are laminated or bonded on a same substrate, as described in a patent document 1 or the like. Moreover, if recording is performed on the dual-layer type, i.e. two-layer type optical disc, e.g. a two-layer type DVD-R disc, an information recording apparatus, such as a DVD recorder, focuses a laser beam for recording on a recording layer located on the front side (i.e. on the closer side to an optical pickup) viewed from the irradiation side of the laser beam (referred to as a “L0 layer” as occasion demands in the application), to thereby record data into the L0 layer in a heat change recording method (in other words, an irreversible recording method), and it focuses the laser beam, through the L0 layer or the like, on a recording layer located on the rear side (i.e. on the farther side from the optical pickup) viewed from the irradiation side of the laser beam (referred to as a “L1 layer” as occasion demands in the application), to thereby record information into the L1 layer in the heat change recording method. On the other hand, if the recording is performed on a two-layer type DVD-RW disc, the information recording apparatus, such as a DVD recorder, focuses the laser beam for recording on the L0 layer, to thereby record data into the L0 layer in a phase change recording method (in other words, a reversible recording method), and it focuses the laser beam on the L1 layer through the L0 layer, to thereby record information into the L1 layer in the phase change recording method.
In the information recording medium on which the plurality of recording layers are laminated, there has been developed a technology of maintaining data reliability against scratches or the like by recording disc volume information on the inner circumferential side of the L0 layer and the outer circumferential side of the L1 layer (refer to a patent document 1).
On the other hand, in recording information onto the information recording medium, recording management data (RMD) for managing the information recording is recorded into a recording management area (RMA) disposed on the information recording medium. As a method of using the RMA, for example, in case of write-once one-layer type and two-layer type DVD-R discs, the RMD is updated by writing once the new RMD. Moreover, in case of a rewritable one-layer DVD-RW disc, as the method of using the RMA, in addition to the above method, such a method is employed that the RMA is used for each RMA segment obtained by dividing the RMA. One RMA segment is used for each RMD set, obtained by dividing the RMA segment. Then, the RMD that is valid (in other words, latest) is recorded into the RMD set, except the head of the RMA segment, and a pointer which indicates the position of the RMD set in which the valid RMD is recorded is recorded into the RMD set, located at the head of the RMA segment. That is, in order to read the valid RMD, firstly, the pointer is obtained by referring to the RMD set which is located at the head of the RMA segment, and the valid RMD is read from the RMD set indicated by the pointer. Moreover, by the same operation, the RMD is updated in the RMD set in which the valid RMD is recorded.
Patent document 1: Japanese Patent Application Laid Open NO. 2005-222628